Relief valve



Feb. 6, 1945. w, ERNST 2,368,754

RELIEF VALVE Filed Feb. 13, 1943 INVENTOR WALTER ERNST BY trwflm'... a you/14m;

ATTORNEY Patented Feb. 6, 1945 RELIEF VALVE Walter Ernst, Mount Gilead, Ohio, assignor to The Hydraulic Development Corporation, Ina, Wilmington, Del., a corporation .0! Delaware Application February 13, 1943, Serial N0. 475,7 4]

3 Claims.

This invention relates to valves and, in particular, to improvements in relief valves. which, in response to a predetermined pressure acting thereupon, release an outlet opening to relieve pressure therethrough. V

Most of the relief valves heretofore known have the drawback that, when using high pressures and correspondingly Strong control springs, the valve member vibrates violently and frequently causes breakage of delicate gages connected thereto. Moreover, these known valves make it impossible to stabilize the desired opening or releasing pressure for the valve.

Accordingly, it is an object of this invention to provide a relief valve which will overcome the above mentioned drawbacks.

Another object of the invention consists in the provision of a relief valve having a fluid operable differential valve member for controlling the release of pressure fluid from an inlet port of the valve through an outlet port thereof, and being provided with a spring arranged in a spring chamber for urging the valve member into closing position, while restricted fluid connection is continuously established between said inlet port and said spring chamber.

It is another object of-the invention to provide a relief valve having a valve member with a differential piston portion and being provided with a spring arranged in a spring chamber and urging the-valve member into closing position, in which fluid pressure is conveyed from one 'area of said difierential piston portion to an opposed area thereof for aiding said spring in its tendency to urge the valve member into closing osition, while a restricted fluid connection is provided between said'flrst mentioned area of the differential piston portion and said spring'chamber.

A further object of. the invention consists in the provision of a relief valve as set forth in the preceding paragraph, in which the smaller area of two opposed areas of the differential piston portion of the valve member is continuously hydraulically connected to an auxiliary relief valve arranged to open prior to the opening ofthe differentlal valve member.

It is a still further object of the invention to provide a relief valve having a differential valve member for controlling the fluid connection between an inlet port and an outlet.port of said valve, in whch the valve member in its closed povalve member for causing the latter rapidly to move into position for establishing fluid connection between said inlet and outlet ports.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the ac-' companying drawing which, by way of example, illustrates an embodiment of the"lnvention in connection with a hydraulic circuit.

Referring now to the drawing in detail, the structure shown therein comprises. a valve casing I, in which is reciprocably mounted a plunger 2. The plunger 2 has an extension 3 extending into a. spring chamber 4 which latter is connected to the valve casing I in any convenient manner. According to the drawing, the spring chamber 4 threadedly engages the valve casing/L r Connected to the extension 3 by means of a nut 5 is a plate 6 on which rests the lower end of the spring I. The upper end of this spring I engages the bottom of the spring chamber 4. Threaded into the upper portion of the Spring chamber 4 is a plug 8, which tightly closes a corresponding opening in the spring chamber 4;

The extension ,3 of the plunger 2, passes through a difierential chamber 9 which is in fluid communication with the spring chamber '4 a through a narrow passage-way 10. The plunger 2 is provided with a bore H which is in fluid calm munication with the difierential chamber.- 8 through a passage-way l2, having a diameter less than the diameter of the passageway Ill. The plunger 2 controls the fluid communication betweenthe inlet port 13 and outlet port. The

inlet port l3 has connected thereto, a conduit 15 which leads to a four-way valve it.

Also connected with the four-way valve ii are conduits I1, I8 and IQ of which the conduit I1 is an exhaust conduit and'may be connected to a fluid reservoir or tank 20. The conduit l9 leads to the upper portion of a cylinder 2i having reciprocably mounted therein the plunger 22. The conduit l8 leads to thelower portion of the cylinder 2 l.

The tank 20 is connected through a conduit 23 with the suction side of a fluid pressure-source sltion is hydraulically balanced, while an aux- 1 iliary relief valve is hydraulically connected with said valve member and adapted'to open at a predetermined pressure to thereby unbalance said 24 such as a pump, the pressure side oi which is connected through a conduit 25 with-theconcluit I5.

Also connected with the tank 20 is a conduit 2 leading to the outlet port H in the valve casing I. The tank 20 has furthermore connected thereto a conduit 2! leading to a port 28 man auxiliary 'valve, generally designated 20.. The

port 28 is controlled by an auxiliary plunger which, in the position shown in the drawin prevents fluid connection between the port 28 and a passageway 3| and also between the port 28 and bore 32. The bore. 32 is provided in a connection 33 which threadedly engages a bore in the valve casing I and also threadedly engages a bore 35 in the auxiliary valve 29.

When the auxiliary plunger 30 is in its retracted position it establishes fluid connection between the bore 32 and the port 28 and also between the passageway 3| and the port 28. The passageway 3I leads into a bore 34 which is threadedly engaged by an auxiliary spring chamber 36, housing a spring 31. The left side of the spring 31 engages the adjacent portion of the auxiliary spring chamber 36 while the opposite end of the spring 31 engages a plate or washer 38. plunger 38 and due to the spring 31 urges the .plunger 30 continuously to the right. The thrust of the springs 'I and 31 may be adjusted by adlusting the spring chamber 4 and auxiliary spring chamber 36, respectively.

Operation The action of the relief valve according to the present invention will appear best from a brief description of the operation of the reliefvalve in connection with the hydraulic circuit shown in the drawing. It may be assumed that all parts occupy the position shown in the drawing while the four-way valve I6, which may be of any standard type, occupies a neutral position in which fluid connection'between conduits I5, II, I8 and I9 is interrupted. If it is now desired to carry out a downward stroke of the plunger 22, the operator shifts the four-way valve I6 into position for establishing fluid connection between the conduits I and I9 while simultaneously placing the conduits I8 and I! in fluid communication with each other.

Then, as soon as the operator starts the pump 24, pressure fluid delivered by the pump, passes through conduits I5, four-way valve I6 and conduit I9, into the upper portion of the cylinder 2I where it acts upon the plunger 22 so as to -move the same downwardly. Fluid expelled by the plunger 22 during its downward movement,

The plate 38 engages the head 39 of the passes through conduit I8, four-way valve I6 and conduit IT to an exhaust or to the tank 28.

The fluid pressure prevailing in the conduits I5 is also conveyed to the port I3 where it acts upon the adjacent annular area 40 of the plunger 2 and also upon the bottom area 4I. Pressure fluid also passes from the port I3 through the narrow passageway I2, into the differenial chamber 9 and from here through the passageway I0 intothe spring chamber 4.

It will be noticed that the plunger 2 is substantially balanced in view of the fact that the pressure acting upon the areas 48 and 4|, is

counteracted (by the pressure acting on the differential area 42 plus the pressure acting in the spring chamber on the exterior of the extension 3. In this way, a relatively light spring A I, is suflicient to hold the-plunger 2 in its closed position. The pressure prevailing in the differential chamber 9 is also conveyed through bore 32 to the plunger 30.

When the plunger 22 has cached the end of 'its downwardstroke or encounters undue rewhich the auxiliary valve 28 has been set, the

pressure acting on the plunger 30 overcomes the spring 31 and moves the-plunger toward the left, to thereby establish fluid connection between the bore 32 and the exhaust conduit 21. The fluid expelled from the bore 34 during this leftward movement of the plunger 30 passes through the passageway 3|, to the port 28. As a result of this leftward movement of the plunger 38, the pressure in the differential chamber 9, is rapidly relieved, and fluid is exhausted through port 28 faster than fluid will be conveyed from the bore II through the narrow passage-way I2 into the differential chamber 9. Consequently. the equilibrium of the plunger 2 previously prevailing, in view of the pressure acting on the areas 40 and M on one hand, the pressure acting on the area 42 and extension 3, on the other hand, is disturbed permitting the pressure acting on the areas 40 and 4| of the plunger 2 to lift the same almost instantaneously, thereby establishing fluid connection between the inlet port I3 and outlet port I4, so that fluid pressure prevailing in the conduit I5 is released through the conduit 26. While the extension 3 moves into the spring chamber, the fluid expelled from the spring chame ber, passes through the passageway I0 into th diflerential chamber 9.

On the other hand, when the plunger 2 returns to its closed'position, fluid passes from the differential chamber 9, into the spring chamber through the passageway III. In this way, a dashpot eflect is obtained. It has been found that the valve according to the present invention opens rapidly and does not chatter, a drawback which has been encountered with most relief valves heretofore known. As soon as the pressure in the conduit I5 drops again, the balance of the plunger 2, is substantially restored and the spring I returns the plunger 2 to its closing position. Also, the pressure drop in the differential chamber 9 and bore 32, allows the spring 31 to move the plunger 30 back into its closed position shown in the drawing. All parts of the relief valve now again occupy the position shown in the drawing.

By shifting the valve I8 so as to establish fluid connection between the conduits I5 and I8, while connecting the conduits I9 and I! with each other, the pressure fluid delivered by the pump 24 will bring about a retraction stroke of the plunger 1 ture shown in the drawing but also embraces all modifications which come within the scope of the appended claims.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is: a

i. In combination in a valve havinga cylindrical bore, a cylindricalvalve plunger reciprocable in said bore and controlling fluid connection between an inlet port and an outlet port, said valve plunger having an effective large area adjacent said inlet port and an opposed smaller area hydraulically connected to said larger area by a restricted passageway in said plunger, a closed casing connected to said valve, an extension member connected to said plunger and extending into said casing, yielding means continuously actfor establishing fluid connection between said smaller area and an exhaust.

2. In combination in a valve having'an inlet port and an outlet port, a valve member having opposed differential areas and operable for selectively preventing or establishing fluid communication between said ports, a closed casing connected to said valve, an extension member connected to said plunger and extending into said casing, yielding means in said casing arranged to continuously act upon said extension member to urge said valve member into position for preventing fluid communication between said ports,

restricted fluid connection for continuously establishing fluid communication between said casing and said diflerential areas; and pilot relief valve means responsive to a predetermined pressure acting on one of said differential areas for establishing fluid connection between said lastmentioned area and an exhaust 3. In combination in a valve having an inlet port and an outlet port. plunger means reciprocable in said valve and having a large area adjacent said inlet port and an opposed smaller area, said areas being continuously hydraulically interconnected through a restricted passageway in said plunger means, an extension connected to said plunger means, and extending into a closed spring chamber, spring means in said spring chamber for acting on said extension to continuously urge said plunger means into a first position for preventing fluid connection between said ports, a restricted passageway having a section larger than the section of said first-mentioned passageway for continuously 'establishing fluid connection between said spring chamber and said smaller area, and pilot relief valve means responsive to a predetermined pressure acting on said smaller area for connecting said area to an exhaust to thereby bring about movement of said plunger into position for establishing fluid communication between said ports.

WALTER ERNST. 

